As part of the DARPA Spectrum Collaboration Challenge, a team of Drexel University undergraduate students, graduate students, and professors developed a Collaborative Intelligent Radio Network (CIRN). Some information about the DARPA SC2 competition is below:
We named our CIRN design “Dragon Radio” to honor our University mascot, the Drexel Dragon. The Dragon Radio team is made up of undergraduate students, graduate students, and several professors from electrical and computer engineering as well as computer science. Our team possesses skills in:
Full radio protocol stack protocol design & development
SDR Host Libraries: Liquid DSP, Liquid USRP, GNU Radio
Automation of software quality regression testing
Machine Learning - statistical and neural networks
Dragon Radio is a full-featured software-defined radio of our own design. This radio utilizes a TUN/TAP interface to allow for seamless integration with standard Linux network traffic test applications and routing protocols. The PHY layer of Dragon Radio is based on the open-source liquid-dsp communications signal processing framework, which provides well-tested modem functions for Fourier-based multi-carrier modulations, Orthogonal Frequency Division Multiplexing (OFDM), as well as single-carrier Quadrature Amplitude Modulation (QAM) and Gaussian Minimum Shift Keying (GMSK). It also includes an interface to an open-source Forward Error Correction (FEC) library. We selected liquid-dsp over GNU Radio as the basis of Dragon Radio because we required full control over scheduling, data flow, and transmission timing. The PHY, Media Access Control (MAC), and datalink layers of the radio are written in C++. This functionality is exposed to Python via pybind11, allowing control and spectrum sharing policies to be implemented in a high-level language. The combination of high-performance lower layers with high-level control allows testbed users with diverse research interests and backgrounds to immediately get up-and-running with the Radio on our testbed.
The radio makes extensive use of both parallelism and concurrency. For example, a bank of demodulator threads acts in parallel to demodulate multiple radio channels simultaneously, and C++ atomics are used to coordinate concurrent radio signal reception and demodulation. In the hybrid FDMA/Time Division Multiple Access (TDMA) MAC we have developed, parallelism enables frequency diversity, and concurrency decreases latency because demodulators do not need to wait for an entire TDMA slot’s worth of data to have been received before demodulation can begin.
We are successfully leveraging Dragon Radio for research and education at Drexel. The radio is being used in SDR-based research, and is also being used for both formal and informal coursework at Drexel. In addition, we are advising several undergraduate students participating in Drexel’s Vertically Integrated Projects (VIP) Program. Depending on their interests, small teams of VIP students are given research tasks that build upon Dragon Radio’s software as a platform for further discovery.